In flat panel displays such as a liquid crystal display, a plasma display and an organic electro-luminescent display, and display devices such as a touch panel, a transparent electrode formed of a transparent conductive oxide such as indium tin oxide (ITO) is used. Patterned wiring is connected to this transparent electrode for the purpose of giving a voltage from the outside or detecting an electric potential on the transparent electrode. As the patterned wiring, those obtained by forming a silver paste by a screen printing method or the like are widely used. Generally, in a display device, wiring is pattern-formed so as to be routed along the periphery of a transparent electrode as schematically shown in FIG. 6. By using a decorated base or the like, the display device is assembled such that the wiring is not visually recognized from the outside.
Patterns of routed wiring tend to be complicated as the definition and function of display devices are enhanced. In the case of touch panels, for example, capacitive touch panels and resistive touch panels, which allow multi-point input (multi-touch), have recently come into the spotlight. In these types of touch panels, a transparent conductive thin film is patterned in a predetermined shape (e.g. stripe shape) to form transparent electrodes, and patterned wiring is formed between each transparent electrode and control means such as an IC. While patterns of wiring become complicated as described above, it is desired to increase an area ratio of a display region in a display device by further narrowing a peripheral region that is decorated so that routed wiring is not visually recognized (narrowing of a frame). However, in the aforementioned method of printing a silver paste, there is a limitation to reduction of a line width of an electrode, and therefore it is difficult to further narrow a frame of a display device.
For further narrowing a frame of a display device, it is necessary to reduce the width of patterned wiring and use a wiring material having high conductivity in order to suppress an increase in resistance of wiring. From such a view point, a method has been proposed in which a transparent conductive thin film 25 is formed on a base 1, a metal layer 3 formed of copper is formed thereon to prepare a laminate 11, and the metal layer 3 and the transparent conductive thin film 25 are sequentially selectively removed by etching to perform patterning as shown in FIG. 4 (for example, Patent Document 1).
On the other hand, in addition to the aforementioned requirement of narrowing a frame, it is desired to use a low-resistance transparent conductive thin film for improvement of the sensor sensitivity and resolution of a transparent electrode. Particularly in the capacitive touch panel, a minute change in electrostatic capacity between transparent electrodes is sensed to detect a position, and it is desired to lower the resistance of a transparent conductive thin film for improvement of the accuracy of positional detection and reduction of response time. Further, resistance property is of vital importance in determination of the sensor sensitivity and the like, and therefore it is important that the transparent conductive thin film retains stable resistance property during mass production.